Primer for airbrushing;

The light grey acrylic should be ok as an undercoat. Just don't treat it as a sandable primer. If you sand it, it doesn't sand cleanly and may crack and flake, leaving ragged edges/pits. However, if it's just a base coat after all your filling/sanding etc, it should be fine.

Thank's Guy's.

Hawkeye - I had considered using a Tamiya matt light grey as a primer (as you have advised in a similar thread) as it acrylic & not in a spray can. Good to know you do this, I will give it a try

 

I actually use Tamiya acrylic flat Sky Grey as my primer of choice. Works wonderfully—if you bother to clean the plastic surface adequately and allow the paint to cure fully. On that latter note, I generally heat cure my paint jobs in a forced air food dessicator just to save time. There are simpler and cheaper solutions to the heat curing that have been discussed multiple times, here and elsewhere: essentially, a sturdy box, a light bulb, and a small fan.

Not much point using low VOC paints if you're going to prime with a high VOC primer, IMHO…

My primary primers are simply the flat light colored model paints. I stock up on flat white and light gray.

I will use Mr Surfacer occassionally, especially on a build that has the need for fillers.

I don't generally use it s a primer but I have experimented with putting Tamiya Liquid Surface Primer through an airbrush. Though it's a "synthetic lacquer" based product, I have been able to thin it using methylated spirits and it goes on very smoothly.

Tamiya LSP comes in grey or white. It smells like a lacquer based product but is fully soluble in methylated spirits (at least it is in our local blend of metho) whereas Mr Surfacer is not.